# file://${PATH_MAIN_REPO_FN_DIR}/dir_cr_f_/_cr_f_/_debug/loop_intead_var/loop_1.sh

    for ((i = 0; i < 4; i++)); do

        ptr=adr_$i
        eval adr_$i=$i$i$i
        echo "\$ptr=" $ptr       # name of value in loop
        echo "\${!ptr}=" ${!ptr} # volume of value in loop

    done
    # adr_1="onnon"
    # for ((i = 0; i < 3; i++)); do
    #     # ptr=adr_$i
    #     # eval adr_$i=$i$i$i
    #     echo
    # done

    echo "\$adr_1=$adr_1"
    echo "\$adr_2=$adr_2"
    echo "\$adr_3=$adr_3"

# file://${PATH_MAIN_REPO_FN_DIR}/dir_cr_f_/cr_f_.sh

        for ((i = 0; i < 100; i++)); do

            vi=vi"$i"_cr_f_
            vr=vr"$i"_cr_f_

            if [ -n "${!vi}" ]; then

                if [ -z "${!vr}" ]; then # ← see 'man test' for available unary and binary operators.
                    eval vr=vr"$i"_cr_f_="v$i$i$i"
                fi

                echo_deb_ $echo_cr_f_ "--- v2f_ ${!vi} $res_file ${!vr} ---" #sistem info mesage
                v2f_ "${!vi}" "$res_file" "${!vr}"
            fi

        done